Differential D2818 Diff 12351 source/gui/Scripting/JSInterface_IGUIObject.h

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source/gui/Scripting/JSInterface_IGUIObject.h

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	* You should have received a copy of the GNU General Public License			* You should have received a copy of the GNU General Public License
	* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.			* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
	*/			*/

	#ifndef INCLUDED_JSI_IGUIOBJECT			#ifndef INCLUDED_JSI_IGUIOBJECT
	#define INCLUDED_JSI_IGUIOBJECT			#define INCLUDED_JSI_IGUIOBJECT

	#include "scriptinterface/ScriptInterface.h"			#include "scriptinterface/ScriptInterface.h"
				#include "js/Proxy.h"

	namespace JSI_IGUIObject			class CText;

				namespace JSI_GUI
				{
				class GUIObjectFactory;

				/**
				* Handles the js interface with C++ GUI objects.
				* Proxy handlers must live for at least as long as the JS runtime
				* where a proxy object with that handler was created. The reason is that
				* proxy handlers are called during GC, such as on runtime destruction.
				* In practical terms, this means "just keep them static and store no data".
				*
				* Function properties are defined once per IGUIObject type and not on each object,
				* so we fetch them from the GUIObjectFactory in the CGUI (via the object).
				* To avoid running these fetches on any property access, and since we know the names of such properties
				* at compile time, we pass them as template arguments and check that the prop name matches one.
				*
				* GUI Objects only exist in C++ and have no JS-only properties.
				* As such, there is no "target" JS object that this proxy could point to,
				* and thus we should inherit from BaseProxyHandler and not js::Wrapper.
				*/
				class GUIProxy : protected js::BaseProxyHandler
				{
				friend class GUIObjectFactory;
				public:
				GUIProxy();
				virtual ~GUIProxy() {};

				private:
				// See GUIObjectFactory on why we want a long-lived proxy.
				static GUIProxy singleton;

				// Handler got object.x
				virtual bool get(JSContext* cx, JS::HandleObject proxy, JS::HandleValue receiver, JS::HandleId id, JS::MutableHandleValue vp) const final;
				// Handler for object.x = y;
				virtual bool set(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, JS::HandleValue vp,
				JS::HandleValue receiver, JS::ObjectOpResult& result) const final;
				// Handler for delete object.x;
				virtual bool delete_(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, JS::ObjectOpResult& result) const final;

				// The following methods are not provided by BaseProxyHandler.
				// We provide a default that does nothing.

				// The JS code will see undefined when querying a property descriptor.
				virtual bool getOwnPropertyDescriptor(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::HandleId UNUSED(id),
				JS::MutableHandle<JSPropertyDescriptor> UNUSED(desc)) const
				{
				return true;
				}
				// Throw an exception is JS code attempts defining a property.
				virtual bool defineProperty(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::HandleId UNUSED(id),
				JS::Handle<JSPropertyDescriptor> UNUSED(desc), JS::ObjectOpResult& UNUSED(result)) const
				{
				return false;
				}
				// Return nothing.
				virtual bool ownPropertyKeys(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::AutoIdVector& UNUSED(props)) const
				{
				return true;
				}
				// Return nothing.
				virtual bool enumerate(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::MutableHandleObject UNUSED(objp)) const
				{
				return true;
				}
				// We are not extensible.
				virtual bool preventExtensions(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::ObjectOpResult& UNUSED(result)) const
				{
				return true;
				}
				virtual bool isExtensible(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), bool* extensible) const
				{
				*extensible = false;
				return true;
				}
				};

				/**
				* A GUIObjectFactory is created by CGUI for each object definition it has.
				* This class is responsible for creating the JS counterparts to C++ objects,
				* which are Proxy objects implement GUIProxy.
				*
				* A word on function properties.
				*
				* Some properties of JS-GUIObjects are functions, which must exist in the JS compartment
				* (get returns the JSNative function, which then gets called from JS code).
				* We could create them as properties of the newly created JS-GUIObject, but that would
				* mean we have n-handlers * GUI objects definitions of the same function. We could create them
				* everytime they are asked for, but that seems rather inefficient.
				* It seems easier to create them once and always return the same JS functions.
				* However, the lifetime of those JS functions must be the same as the lifetime of the compartment,
				* (unlike the proxy handler which lives forever), so we must store them in an object whose lifetime
				* is tied to the CGUI lifetime. We could, for now, store them in the IGUIObject directly, since we don't
				* really create/destroy objects at runtime, but that's preventing future evolution.
				* The simplest solution is to store them in the GUIObjectFactory.
				*/
				class GUIObjectFactory
	{			{
	extern JSClass JSI_class;			friend class ::JSI_GUI::GUIProxy;
	extern JSFunctionSpec JSI_methods[];			public:
				/**
				* This is the "least derived" object type that this factory can work with.
				* A pointer to the c++ object is stored in the private data of the proxy, which is void*.
				* We need to know what type to use when writing and reading the pointer.
				* This is that type.
				*/
				using cppType = IGUIObject;

	void RegisterScriptClass(ScriptInterface& scriptInterface);			GUIObjectFactory(ScriptInterface& scriptInterface);
				JSObject* CreateObject(JSContext* cx);
				protected:
				/**
				* Call the "callable" member function, correctly converting input and output from and to JS.
				* This is a generic method that does no particular transformation on JS inputs, provided for convenience.
				* If some specific pre-processing of arguments is wanted, it should be specialised.
				*
				* Templated on on objType because `using cppType` isn't virtual-like.
				*
				* TODO: this method will generally not work for member functions with multiple overloads.
				* It sounds fixable, but rather difficult.
				*/
				template <typename objType, typename funcPtr, funcPtr callable>
				static bool scriptMethod(JSContext* cx, unsigned argc, JS::Value* vp);

	bool getProperty(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::MutableHandleValue vp);			std::map<std::string, JS::PersistentRootedFunction> m_FunctionHandlers;
	bool setProperty(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::MutableHandleValue vp, JS::ObjectOpResult& result);			static js::Class m_ProxyObjectClass;
	bool deleteProperty(JSContext* cx, JS::HandleObject obj, JS::HandleId id, JS::ObjectOpResult& result);			};
	bool toString(JSContext* cx, uint argc, JS::Value* vp);			class TextObjectFactory : public GUIObjectFactory
	bool focus(JSContext* cx, uint argc, JS::Value* vp);			{
	bool blur(JSContext* cx, uint argc, JS::Value* vp);			public:
	bool getComputedSize(JSContext* cx, uint argc, JS::Value* vp);			using cppType = CText;
	bool getTextSize(JSContext* cx, uint argc, JS::Value* vp);			TextObjectFactory(ScriptInterface& scriptInterface);
				};
	}			}

	#endif // INCLUDED_JSI_IGUIOBJECT			#endif // INCLUDED_JSI_IGUIOBJECT